The objective of the proposed research is to discern the psychosocial and behavioural effects of national level tobacco control policies on adult smokers and adolescents in two developing countries in Southeast Asia (Thailand and Malaysia), and to determine how these groups are affected by three interrelating factors: (1) beliefs and other psychosocial variables of the individuals (Host factors); (2) environmental, cultural, and social context (including policies); and (3) agent factors (tobacco companies and their actions). A secondary set of questions relates to how effects found in Malaysia and/or Thailand compare to policy effects in high income countries such as Canada, United States, United Kingdom, and Australia (Project 1). This questions is relevant to extending our understanding of the generality of policy effects across countries that vary greatly in culture and income. These study aims wilt be addressed by surveying broadly representative cohorts of 4,000 adult smokers and 2,000 adolescents, equally sampled from the two countries, over three waves time two years apart. Data collected in these surveys wilt also be linked to Project 3 which will examine how design features of cigarettes related to usage pattern and beliefs about product safety. A number of tobacco policy changes are anticipated in Thailand and Malaysia over the next 5 years. Graphic warnings are to be implemented in Thailand from January 2005 and are expected in Malaysia around 2007, higher cigarette taxes are expected in both countries, a mass media campaign is expected in Malaysian to encourage Moslems who smoke to quit for Ramadan. This study will provide a means for investigating the effect of these policies on beliefs and smoking habits and direct comparison to the impact of similar policies enacted in developed countries.